Mumbai University > Electronics Engineering > Sem 8 > Advanced Networking Technologies

Marks: 7M

1. Bluetooth devices can create both point-to-point and point-to-multipoint connections.
2. A connection with two or several (maximum 8 devices) devices is a Piconet where all devices follow the same frequency-hop scheme.
3. To avoid interference between devices, one of the devices automatically becomes a master of the Piconet.
4. In each slot, a packet can be exchanged between the master (M) and one of the slaves (S).
5. Packets have a fixed format (see Figure). A Bluetooth packet format is based on one packet per hop and a basic 1-slot packet of 625 µs that can be extended to 3-slot (1875 µs) and 5-slot (3125 µs).
6. A frame format allows the master to poll multiple slaves. Each packet begins with a 72-bit access code that is derived from the master identity and is unique for the channel.
7. Every packet exchanged on the channel is preceded by this access code.
8. Recipients on the Piconet compare incoming signals with the access code.
9. If the two do not match, the received packet is not considered valid on the channel and the rest of its contents are ignored.
10. Besides packet identification, the access code is also used for synchronization and compensating for offset. The access code is robust and resistant to interference.